Drill bit



Nov. 29, 1949 vF. THRlFT ET AL DRILL BIT Filed Nov. 19, 1946 MII- 'Patented Nav. 29, i949 g DRILL BIT Fred Thrift, deceased, late of Kingsville, Tex., by Betty Barker Thrift, administratrix, Kingsville, Tex., and Herman E. Davis, Corpus Christl, Tex.

Application November 19, 1946, Serial N0. 710,866

s claims. V(ci. 25e-s1) This invention rentes to a drin bit specially designed for use in drilling deep wells.

An object of the invention is to provide a drill bit which is so constructed that the drilling condition of the bit will be indicated to the operator at theground surface so that when the cutting edges have been worn away the bit may be withdrawn for repairs before it has been worn to such an extent that it cannot be repaired.

This indication to the operator will make it: unnecessary to withdraw the drill bit from the well in order to determine its cutting eiliciency. At the present time drill bits are faced with a 'hard metal which extends a distance back from the cutting edges of the bit. When this hard material is worn away and the driller continues to run the bit the wear on the bit body is ex-i cessive and often ruinous to such an extentthat the bit cannot be repaired and resharpened.

whose upper end is reduced and externally threaded forming a shank Ia yonto which the drill collar 2 is threaded. This collar is provided for the attachment of the drill bit vto a conventional tubular drill stem bymeans of which the drill bit is rotated from the ground surface.

The shank is provided with an axial bore 3 and leading from the interior of the bore are the channels 4, 4. These channels lead downwardly through the body of, the drill and terminate on the forward faces of the cutting blades Ib, lb whose lower ends are provided with the forwardly pitched transverse cutting edges Ic, Ic. These cutting edges and, the forward faces of the blades are usually covered with a coating of hard metal.

As clearly shown in Figures 2 and 4, the bore 3 extends down through the shank and partly through the drill body and being of greater With the present invention the driller will be intransverse diameter than the thickness of the formed just when to withdraw vthe drill bit for repair thus making it unnecessary to withdraw the bit to the ground surface for inspection.

It is a further object of the present invention to provide a drill bit of the character described which is of such construction that it will allow the drilling fluid within the drill stem to quickly drain out when the drill stem and drill bit are withdrawn for the purpose of replacing the drill bit with a new one.

With the type of bit herein described, when the cutting edges have worn to such an extent that the drill is no longer usable, for making a hole, flushing fluid may be forced down through the drill stem so as to wash out and ilush the well bore as will be more specifically hereinafter explained.

Other objects and advantages of the present invention will be apparent from the following specification which is illustrated by the accompanying drawings, wherein- Figure 1 is a iront elevation of the drill bit, partly in section.

Figure 2 is a Vertical, sectional view taken on the line 2-2 of Figure 1.

Figure 3 is a cross-sectional view taken on the line 3-3 of Figure 1 and;

Figure 4 is a view similar to that shown in Figure 2 showing the parts in the position that they will assume when the cutting edges of the bit have worn away.

Referring now more particularly to the drawings, wherein like numerals of reference designate the same parts in each of the figures, the

numeral I designates the body of the drill bit blade portion of the drill bit the bore emerges on each side in the openings 5.

In drilling the drilling fluid is forced under pressure down through the drill stem and drill collar into the bore 3 and while drilling it is necessary that the bore be closed beneath the upper ends of the channels li as otherwise the drilling llluid would pass on down through the bore and out through the openings 5 and would not pass through the channels 4. It is necessary, for successful drilling, that the drilling fluid pass through the channels t in order to cleanse and lubricate the cutting edges of the drill bit.

Therefore, an upwardly opening hydraulic cup 5 is provided and is attached to a piston 'l which is located within the bore 3 and closes said bore. This piston is attached to Vthe upper end of the piston rod 8. Fastened on the lower end of this rod there is a disc 9 having the lateral projections IIJ, I0 which project through the openings 5 on each side.

Pivoted on the rear side of each blade |17 there is a lever II which is mounted on a corresponding fulcrum I2.. The projections I0 engage the inner ends of the corresponding levers.

Attached to the outer ends of these levers are the wires I3, I3 whose lower ends are welded, at the points I4, on the back of the respective blades above the cutting edges. These levers will operate to holdthe Apiston l in its upper position, while drilling, so that the cup 6 will close the bore 3 to force the drilling fluid through the channels 4.

When the cutting edges of the drill bit become worn to a predetermined extent, as indicated by the dotted lines in Figures 1 and 4, the wires I3 are destroyed and the levers ll are allowed to rotate on their fulcrums and the pressure oi the drilling iiuid will force the cup 6 and piston 1 downwardly so as to open the openings 5 and allow the drilling iiuid to freely ow out from the lower end of the drill stem at a greatly reduced pressure. When this occurs the pump supplying the drilling fluid at the ground surface, will increase its speed suddenly and this will indicate to the driller that the cutting edges of the drill bit are worn to such an extent that the drill should be withdrawn .for repairs; but as long as the pump pressure remains normal the driller will know that the cutting edges of the drill blt are in good operating condition.

When the piston and hydraulic cup 6 have moved downwardly to the position indicated in Figure 4 and it is desired to ush the well ushing fluid may be readily pumped down through the drill stem and through the openings 5 and will return to the ground surface.

Upon withdrawal of the drill stem and drill bit from the well the drilling iiuid in the drill stem will readily drain out and be left in the well bore; otherwise upon withdrawal of the drill stem as it is broken up in the derrick the drillingiluid therein would spill out over the derrick floor and interfere with the operations being carried thereon.

The drawings and description are illustrative merely while the broad principle of the invention will be dened by the appended claims.

What we claim is:

l. A drill bit comprising, a body whose upper end is formed into a shank which is provided with a bore leading downwardly therethrough from its upper end and terminating in a side opening, cutting means on the lower end of the body, said body having channels which lead from the bore and terminate on opposite sides of the bit, a closure in the bore means on the drill bit normally holding the closure in position to close said bore, means maintaining said holding means in active position and arranged to be disrupted in response to wear on the cutters to release the holding means to allow the closure to move downwardly, in response to the pressure of fluid in the bore, to open the bore.

2. A drill bit including a body whose upper end is formed into a shank having a bore whose lower end terminates in side openings, cutting means on the lower end of the body, slidable iiuid obstructing means in the bore above said openings, means for locking said obstructing means in iixed position to obstruct the flow of fluid downwardly through the bore, said locking means including an element which is anchored to thebit near the lower end thereof and whose anchor--v age is disrupted by the wear,on the cutters to release the locking means to allow the obstructing means to move downwardly, in response to the pressure of fluid in the bore above, to open the bore and allow the flow of uid from the bore through said openings.

3. A drill bit comprising, a body having an axial bore leading downwardly therethrough from its upper end and terminating in a side opening, cutting means on the lower end of the body. said body having channels which lead from the bore and terminate on opposite sides of the drill bit, a piston in the bore beneath the upper ends of said channels, means on the drill bit. which interlock and hold the piston in position to close the lower end of the bore, means maintaining said interlocking means in interlocking relation and arranged to be disrupted, in re\ sponse to wear on the cutters to allow the interi locking means to release the piston whereby the piston will be moved downwardly by the pressure of iiuid in the bore to open the bore.

4. A drill bit comprising, a body having an axial bore leading downwardly therethrough from its upper end and terminating in a side opening, cutting means on the lower end of the body, a piston, while in one position, closing the lower end of the bore above said opening, means for locking the piston in said position in the bore, a tie member anchored at one end to the locking means and at its other end to the bit near the lower end thereof and maintaining the locking means in active, or locking, position.

5. A drill bit comprising, a body having an axial bore leading downwardly therethrough from its upper end and terminating in a side opening, cutting means on the lower end of the body, a piston closing the lower end of the bore above said opening while in one position, means for locking the piston in said position in the bore, a tie member anchored at one end to the locking means and at its other end to the bit near the lower end thereof and maintaining the locking means in active, or locking, position, said locking means being releasable, upon rupture of the tie member to allow the downward movement of the piston, in response to uid pressure in the bore, to open said bore.

6. A drilling tool comprising, a drill bit body whose upper end is formed into a shank having a bore leading downwardly through the shank and terminating in a side opening, a tubular drill stem whose lower end is connected to the shank, cutting means on the lower end of the body, a closure in the bore, means on the drill bit including a tie element for maintaining said closure in position to close said bore, said tie element being anchored, at one end to the drill bit near the lower end thereof whereby wear of the lower end of the drill bit will destroy said anchorage to release said maintaining means, said closure, when released, being movable by the pressure of the drilling iiuid in the stem downwardly to open the bore.

BETTY BARKER THRIFT, Administratri, Estate of Fred Thrift, Deceased.

HERMAN E. DAVIS.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PA'I'ENTS Number Name Date 2,239,106 Krall Apr, 22, 1941 2,296,183 Richard Sept. 15, 1942 

